Sequence diversity of the oprI gene, coding for major outer membrane lipoprotein I, among rRNA group I pseudomonads

The sequence of oprI, the gene coding for the major outer membrane lipoprot ein I, was determined by PCR sequencing for representatives of 17 species o f rRNA group I pseudomonads, with a special emphasis on Pseudomonas aerugin osa and Pseudomonas fluorescens. Within the P. aeruginosa species, oprI seq uences for 25 independent isolates were found to be identical, except for o ne silent substitution at position 96. The oprI sequences diverged more for the other rRNA group I pseudomonads (85 to 91% similarity,vith P. aerugino sa oprI). An accumulation of silent and also (but to a much lesser extent) nonsilent substitutions in the different sequences was found. A clustering according to the respective presence and/or positions of the Haem, PvuII, a nd SghI sites could also be obtained. A sequence cluster analysis showed a rather widespread distribution of P. fluorescens isolates. All other rRNA g roup I pseudomonads clustered in a manner that was in agreement with other studies, showing that the oprI gene can be useful as a complementary phylog enetic marker for classification of rRNA group I pseudomonads.